Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductor layers over a semiconductor substrate and patterning the various material layers using lithography to form circuit components and elements thereon.
One of the important drivers for improving performance in semiconductor structures is the higher levels of integration of circuits. This is accomplished by miniaturizing or shrinking device sizes on a given chip. For example, FinFET structures and nanowire FET structures are formed to increase the integration density in the semiconductor structures. However, although existing processes for manufacturing FinFET structures and nanowire FET structures have generally been adequate for their intended purposes, as device scaling-down continues, they have not been entirely satisfactory in all respects.